Combined liquid phase and vapor phase oil cracking process



Deb. 13, 1938. B. P. CRITTENDEN 7 COMBINED LIQUID PHASE AND VAPOR PHASEOIL CRACKING PROCESS Filed Oct. 25, 1930 I k v i INVENTOR ATTORNEXSPatented Dec. 13, 1938 UNITED STATES PATENT OFFICE COMBINED LIQUID PHASEAND VAPOR PHASE OIL CRACKING PROCESS Application October 25, 1930,Serial No. 491,101

20 Claims.

This invention relates to a process by means of which petroleum oils,such as raw crude oil, reduced crude oil and gas oil, may be cracked toproduce anti-detonating motor fuels, commercial gas oil and commercialfuel oil. It includes both liquid phase and vapor phase cracking. Bythis process, a specially selected charging stock, which is segregatedduring the operation, is subjected to liquid phase cracking and thecracked products therefrom are mixed with the raw stock andthe mixtureintroduced into a separator. A particular gas oil fraction segregatedduring the operation is subjected to vapor phase cracking and theproducts therefrom are introduced into the separator with theabove-mentioned mixture. During the process, the incoming raw stock ispreheated by passing it through heat exchangers that are heated byvapors and liquids from the cracking operations.

The invention will be understood from the description of the processwhich may be carried out by an arrangement of apparatus that isillustrated diagrammatically in the accompanying drawing.

In the accompanying drawing the single figure is a diagrammatic viewshowing an apparatus in which the improved process of the presentinvention may be carried out.

In the drawing; reference character I indicates a tank containing asupply of the oil to be cracked. A pump 2 forces the oil from the tank Ithrough the pipe 3, heat exchangers 4, 5, E and 7 in series, and thencethrough the pipe 8 into another pipe l2, where it is mixed with theproducts from the liquid phase cracking coil 9 located in the furnaceID.

A vapor phase cracking coil I! is also located in the furnace H3. Pipesl2 and !3, that are provided with pressure release valves 14 and I5,respectively, lead from the coils 9 and H to a separator iii.

A pipe I! leads vapors from the upper portion of the separator #5through the heat exchangers 6 and 5 in series in each of which a portionof the vapors is condensed. The remaining vapors pass through the pipe18 and upwardly through the bubble tower E9, where more of the vaporsare condensed. The remaining vapors then pass through the outlet pipe2i! and heat exchanger 4 where more vapors are condensed. The finalvapors pass from the heat exchanger 4 through a pipe 2| into a condenser(not shown).

Pipes 22 and 23 lead from the lower portions of the heat exchangers 5and 5 to a pipe 24 that is provided with valves 25, 26 and 21 so locatedthat they can be manipulated in such a manner that the condensates fromthe heat exchangers 5 and 6 can be introduced into the separator IE5 oran accumulator 28 located below the bubble tower l9, or all of thecondensate from the heat exchanger 6 can be introduced into theseparator I 6, while all of the condensate from the heat exchanger 5 canbe introduced into the accumulator 28, or all of the condensates fromthe heat exchanger 6, together With a portion of that from the heatexchanger 5, can be introduced into the separator l6, while theremainder of the condensate from the heat exchanger 5 is introduced intothe accumulator 2B, or all of the condensate from the heat exchanger 5,together with a portion of that from the heat exchanger 6, can beintroduced into the accumulator 28, while the remainder of thecondensate from the heat exchanger 6 is introduced into the separatorIS.

A pump 29 is provided for forcing condensate from the accumulator 28through the pipe 30 into the liquid phase cracking coil 9.

A pipe 3| leads from the lower portion of the bubble tower l9 into astripping column 32, from which a pipe 33, provided with a valve 34,leads to a surge tank 35. A pump 35 is provided for forcing liquid fromthe surge tank 35 through the pipe 31 into the vapor phase cracking coilII. A pipe 38 provided with a valve 39 branches off from the pipe 33 andleads to a cooler 40, from which a pipe leads to a storage tank (notshown).

A pump M is provided for forcing liquid from p the lower portion of theseparator it through the pipe 42, thence through the heat exchanger 1and the pipe 43, and thence through the cooler 44 to a storage tank (notshown).

The operation is as follows: The raw oil, such as crude petroleum,reduced crude oil and gas oil, is forced by the pump 2 from the tank Ithrough the heat exchangers 4, 5, 6 and 1 into the pipe l2, leading fromthe liquid phase cracking coil 9, between the pressure release valve I 4and the separator I6. I have found that about lineal feet of contact inthe pipe I! between the point of mixing and the separator l6 has given avery satisfactory control of the fuel gravity and control of fuelviscosity. The vapors in the separator l6 pass through the pipe l1,while the residue of the oil collects in the bottom of the separator IS.The vapors passing out through the pipe H are passed through the heatexchanger 5, where the relatively high boiling constituents condense andpass out through the pipe 23. The remainder of the vapors then passesint the heat exchanger 5., where somewhat lower boiling constituentscondense and pass out through the pipe 22, the remaining vapors passingthrough the pipe l8 and into the bubble tower is. The condensates fromthe heat exchangers 5 and B that pass to the accumulator 28 are clean,low carbon residue products that are suitable as charging stock for theliquid phase cracking coil 9. The portions of the condensates from theheat exchangers 5 and 6 that are introduced into the separator 16 areused to regulate the gravity of the fuel oil that is desired to beproduced and withdrawn from the bottom of this separator.

A fractionation and condensation of vapors leaving the heat exchanger 5take place in the bubble tower l9, resulting in a separation andsegregation of several fractions. The fraction that is not condensed inthe bubble tower it passes through the heat exchanger 4 where morevapors condense, the condensate returning to the tower l9. Uncondensedvapors pass from the heat exchanger into a condenser through pipe 2|,where they are condensed and the condensate constitutes a commercialmotor fuel. Another fraction is condensed in the bubble tower i9 and iswithdrawn through the pipe 3! into the stripping column 32. A portion ofit is used for the vapor phase cracking operation in coil Ii. Thetemperature in the cracking coil II should be about 1000 to 1100 F.Another fraction which has a higher boiling range than the fractionpassing through the pipe 3|, passes into the accumulator 28 and is used,together with the condensates from the heat exchangers 5 and 6, as thecharging stock for the liquid phase cracking coil &. The temperature inthe cracking coil 9 should be about 875 to 950 F.

A portion of the condensate that passes through the stripping column 32from the lower portion of the bubble tower I9 is withdrawn through thepipe 38 and constitutes the gas oil that is obtained from the process.The remainder of the gas oil from the stripping column 32 passes throughthe pipes 33 and 31 into the vapor phase cracking coil II.

By controlling the gas oil content of the vapors leaving the heatexchangers 5 and 6 and entering the bubble tower l9, as well as thetemperature of the same, and simultaneously controlling the intermediatetemperatures within the bubble tower [9 by spraying back over the top ofthe tower, such a fractionation is caused within the tower that thecondensation of a high boiling range fraction results which isdischarged into the accumulator 28 and a lighter gas oil fraction ofdesired boiling point range and carbon residue content is also separatedand subsequently withdrawn through the pipe 3! into the stabilizingtower or stripping column 32.

The residue of oil that collects in the bottom of the separator "5,together with such portions of the condensates from heat exchangers 5and 6 as are introduced into the separator, pass through the pipe 42,heat exchanger 1 and pipe 33 and cooler 44 and constitute the fuel oilthat is obtained from the process.

By this invention, commercial petroleum fractions can be separated fromcrude petroleum. The crude petroleum or other oil that is to be treatedis preheated by liquids or vapors that have received heat in thecracking coils. The temperature of the mixture of preheated raw materialand efilux from the cracking coil '8 which passes into the separator Hi,can be controlled so that the mixture separates in the separator into avaporized portion that passes out through the pipe I! and a fuel oilfraction of the desired gravity that passes out through the pipe M isobtained having a low total fixed carbon content and low viscosity evenwhen raw material of different characteristics are preheated and chargedinto eiliux pipe l2. However, for the production of fuel oil of thesecharacteristics it is desirable to have a raw material that contains afraction having a specific gravity approximately equal to that of thefuel oil that it is desired to produce. If the material being treateddoes not contain such a fraction but contains a fraction of highergravity, a fuel oil of desired characteristics may still be obtained butwill require an increase in time of contact between the raw materialentering through the pipe 8 and the material passing out of the releasevalve M in the pipe l2. The time of contact may be varied by changingthe point at which the pipe 8 enters the pipe I2; Of course, thesuperheat in the vapors passing out of the pressure release valve I4 isavailable for aiding in completing the final vaporization of the mixturefrom the heating coil 9 and pipe 8.

The heavy gas oil which accumulates in the accumulator 28 as describedabove and is cracked in the cracking coil 9, is free from low boilingfractions and is of a moderately heavy gravity. It contains a very smallamount of fixed carbon or carbon residues and is relatively free fromharmful chemical constituents which would give trouble in the crackingcoil by producing excessive wear or destruction of the cracking coil 1or accessory apparatus and would also carry into the motor fuel that isproduced from the process chemical constituents which would requirecostly chemical treatment to remove the same, resulting in loss ofmaterial and large expense. The fraction from the accumulator 28 is verymuch more suitable for being cracked in the coil 9 to produce motorfuels, gas oils and fuel oils than would be true of a charging stockthat contains large quantities of light fractions and large quantitiesof fixed carbon or carbon residues. This fraction used for charging thecracking. coil 9 permits the use of greatly elevated temperatures inthis coil without requiring increased pressures and the result is theproduction of motor fuel of greatly increased anti-detonating qualities.

By using the condensate that passes out of the bubble tower through thepipe 3! as the charging stock for the cracking coil ll, very desirableresults are obtained in the production of motor fuels, gas oils and fueloils in accordance with this invention. Although even if the motor fuelfraction of the materialpassing out through the pipe l3 into theseparator '56 contains constituents that would be harmful to theoperation of internal combustion engines unless special chemicaltreatment is given thereto, it has been found that by introducing theefilux from the cracking coil H into the separator l6 as describedabove, the materials become mixed and chemical reactions appear to takeplace, with the result that the motor fuel that is obtained from thevapors leaving the separator I6 through the pipe I! possessesexceptionally high antidetonating value and is free from the harmfulconstituents that were present in the efflux from the cracking coil H.In this way, the expensive chemical treatment is avoided and thevolumetric losses in such treatment does not occur.

The harmful constituents appear to remain in the residual oil at thebottom of the separator and pass out in the fuel oil and do not,therefore, remain in the vaporized portions of the efiiux from thecracking coils 9 and H to deposit in the pipes and obstruct the same.

I claim:

1. The process of cracking petroleum oils for the formation of a highanti-knock gasoline, which comprises subjecting the vapors from acracking operation to a fractional condensing operation in which arelatively heavy product and a relatively light product of higherboiling point than the desired gasoline are obtained, heating therelatively heavy product in a confined stream to a cracking temperatureof from 875 to 950 F. and passing the resulting highly heated productsthrough a relatively long transfer line into a separating zone,separating vapors from unvaporized oil constituents in said separatingzone, preheating a charging stock for the process and introducing thesame into the hot oil products in the said transfer line at a pointabout 130 feet along said line from said separating zone whereby themingled products in said transfer line are thoroughly mixed and theirtemperatures substantially equalized prior to being discharged into saidseparating zone, heating said relatively light product to a highcracking temperature of from 1000 to 1100 F. while conducting the samein a confined stream through a heating zone, passing the resultinghighly heated oil constituents from the heating of said light oilproduct into said separating zone, wherein they are mingled with theproducts discharged from said transfer line, subjecting the vaporsseparated in said separating zone to said fractional condensingoperation and condensing a high anti-knock motor fuel product fromVapors uncondensed in said fractionating operation.

2. The process of cracking petroleum oils for the production of a highanti-knock gasoline motor fuel, which comprises producing a relativelyheavy and a relatively light reflux condensate in the crackingoperation, cracking the relatively heavy condensate by heating it to ahigh temperature while passing it in a confined stream through a heatingzone, conducting the resulting products through a transfer line into aseparating zone in which vapors are separated from unvaporized oilconstituents, introducing charge oil stock for the process into thestream of the highly heated products at a point a substantial distancealong the transfer line from said separating zone whereby sufficienttime is allowed for the thorough mingling of the charge oil and highlyheated products prior to their introduction into said separating zone,heating the relatively light reflux condensate in a separate confinedstream to a temperature sufficient to effect cracking thereof in vaporphase, said temperature being substantially higher than the temperatureto which the heavy reflux condensate was subjected, and introducing theproducts resulting from the heating of the relatively light refluxcondensate into said separating zone in intimate contact with the vaporsof said heavy reflux condensate and charging stock to thereby aid inproducing a substantially stable gasoline product.

3. The process of cracking petroleum oils for the formation of a highanti-knock motor fuel, which comprises producing a relatively highboiling point gas oil fraction and a relatively low boiling point gasoil fraction from the vapors produced in the cracking process, said gasoil fractions being relatively low in carbon residue content, separatelycracking the said fractions by heating each fraction to a temperatureparticularly adapted to its conversion in substantial proportion tolower boiling point products, said heating including the heating of therelatively low boiling point gas oil fraction to a substantially highertemperature than that to which the relatively high boiling point gas oilfraction is heated, preheating fresh charging stock for the crackingprecess by passing it in indirect heat exchange with vapors produced inthe cracking operation and intimately mixing it with the high-- lyheated high boiling point gas oil fraction, maintaining the resultingmixed oils in intimate contact for a substantial period of time and thenpassing the same into a vapor-liquid separating zone, introducing thehighly heated products resulting from cracking said low boiling pointfraction into the vapors in said separating zone, and subjecting thevapors separated in said separating zone to fractional condensingconditions to produce said gas oil fractions and said anti-knock motorfuel.

4. The process of cracking petroleum oils for the production of a highantiknock gasoline motor fuel and a marketable fuel oil, which comprisescracking a relatively heavy distillate by heating it to a high crackingtemperature while passing in a confined stream through a heating zone,

conducting the resulting products through a relatively long transferline' into a separating zone in a large chamber in the lower portion ofwhich vapors are separated from unvaporized oil constituents,introducing a preheated relatively heavy residue containing freshcharging stock for the process into the stream of said highly heatedproducts at a point a substantial distance along the transfer line fromsaid separating zone whereby suflicient time is allowed for thoroughmingling of the charge oil and the highly heated products prior to theirintroduction into said separating zone and whereby said fresh chargingstock is heated sufficiently to produce a fuel oil residue of lowviscosity, withdrawing a marketable fuel oil from the lower portion ofthe separating zone and removing it from the system, and subjecting thevapors separated in the separating zone to fractional condensingconditions to separate out a high antiknock gasoline product.

5. The process defined by claim 4 in which a plurality of refluxcondensates of higher boiling point than gasoline are produced in thevapor fractionating operation, and introducing into the separating zonea regulated portion of the higher boiling point reflux condensate to aidin controlling the quality of the fuel oil Withdrawn from the separatingzone.

6. The process of cracking mineral oils which comprises, passing an oildistillate in a confined stream of restricted cross section through aheating zone and therein heating and cracking the said distillate,passing the highly heated and cracked distillate products through atransfer line directly into the lower portion of an enlargedunobstructed vertical vapor liquid separating zone in a large verticalchamber, substantially reducing the pressure on said highly heateddistillate products in said transfer line and introducing directlythereinto a stream of relatively heavy preheated fresh oil chargingstock at a point subsequent to said pressure reduction and at asubstantial distance along said transfer line from said separating zone,whereby the length of contact between said highly heated distillateproducts and said heavy fresh oil charging stock in said transfer lineis sufficient to reduce the viscosity of said stock and produce amarketable fuel oil having a predetermined viscosity, separating theunvaporized fuel oil constituents from the vapors in the lower portionof said separating zone, discharging the separated fuel oil constituentsfrom the bottom of the separating zone and removing them from thesystem, removing the separated vapors from the upper portion of saidseparating zone, fractionating the vapors removed from said separatingzone into a plurality of relatively high boiling point condensatefractions, and selecting condensate having a relatively low carbonresidue content from said fractions to supply at least in part 'saiddistillate oil for said heating zone.

'7. A hydrocarbon oil cracking process which comprises passing arelatively heavy oil through a heating zone and heating the same thereinto cracking temperature under pressure, discharging the heated oil intothe lower portion of a substantially vertical reaction zone in a largevertical chamber maintained under cracking conditions of temperature andpressure, separating the heated oil into vapors and unvaporized oil inthe lower portion of the reaction zone and withdrawing the separatedunvaporized oil from the lower portion of said reaction zone andremoving it from the system, simultaneously heating a lighter oil in asecond cracking zone to a higher cracking temperature than that to whichsaid relatively heavy oil was heated and then discharging the resultingproducts into said reaction zone a substantial distance below the topthereof and above the point of introduction of said heated oil, therebypreventing contact between the vapors of the lighter oil products andsaid unvaporized oil, and commingling the lighter oil vapors with thefirst-mentioned vapors, passing the commingled vapors upwardly throughsaid reaction zone and removing the same from the upper portion thereof,and fractionating and condensing the vapors withdrawn from the reactionzone.

8. The process of converting hydrocarbon oils into anti-detonating motorfuel products, which comprises passing a relatively high boiling pointoil in a confined stream of restricted cross section through a heatingzone and subjecting the stream of oil therein to a temperature andpressure sufficient to effect conversion thereof, conducting theresulting highly heated products from said zone into the lower portionof an enlarged vertical separating zone in a large vertical chamber inthe lower portion of which vapors are separated from unvaporized oilconstituents, the latter of which are collected in the bottom of theseparating zone, withdrawn therefrom and removed from the system,heating and cracking a relatively lighter oil stock in a second crackingzone through which the oil stock is passed in a confined stream ofrestricted cross section, heat ing the said lighter stock to a highercracking temperature than that to which said relatively heavy stock issubjected and then introducing the products from the second crackingzone into said enlarged separating zone at a point substantially belowthe top thereof but above the point of introduction of the hot oilproducts from the first-mentioned cracking zone, whereby the vapors ofsaid relatively lighter oil are brought in contact with the separatedvapors of the relatively heavy oil in said separating zone, passing theresulting mixed vapors upwardly through said separating zone in anunobstructed path and removing the same from the upper portion thereof,and fractionally condensing the vapors withdrawn from the separatingzone.

9. In the art of processing crude petroleum oil for the production ofvaluable products therefrom, the improvement which comprises passing thecrude petroleum oil charging stock to be processed through a primarycondensing zone in indirect heat exchange with high temperature crackedvapors and vapors resulting from the distillation of the crude oil toheat the crude oil and produce fractional condensation of the saidvapors, passing the remaining vapors from said primary condensing zoneinto a secondary fractionating zone to effect further condensation ofrelatively high boiling point constituents contained in the vapors,introducing the heated crude petroleum oil into an enlarged vaporseparating zone in a large chamber in which substantial portions of theoil is vaporized, conducting the resulting vapors to said primarycondensing zone, passing relatively high boiling point condensate fromone of said condensing zones in a confined stream of restricted crosssection and subjecting it to'cracking conditions at a relatively hightemperature, introducing the resulting highly heated products from saidcracking zone into intimate contact with the heated crude oil introducedinto said enlarged separating zone, withdrawing unvaporized oilconstituents separated out in said separating zone from the lowerportion thereof to comprise a fuel oil product of predeterminedviscosity which is removed directly from the system, and withdrawing ahigh anti-knock motor fuel vapor product from said secondaryfractionating zone.

10. The process defined by claim 9 in which at least a portion of thecondensate formed in said primary condensing zone is introduced directlyinto said enlarged separating zoneto aid in controlling the gravity ofthe fuel oil collected in the lower portion thereof.

11. In the art of converting hydrocarbon oils for the production of highanti-knock motor fuel products, the process which comprises passing arelatively light charging stock in a confined stream of restricted crosssection through a heating zone and heating the oil of said stream to ahigh cracking temperature of the order of 1000 F., preheating a crudepetroleum oil charging stock containing heavy residual constituents,introducing the cracked products from said cracking zone and the saidpreheated charging stock into one end portion of an enlarged separatingchamber in which vapors are separated from unvaporized oil constituentswhich are collected in the bottom of the chamber, withdrawn therefromand removed from the system, withdrawing the vapor mixture separated outin said separating zone and subjecting the same to fractional condensingconditions to produce a plurality of fractional condensates of higherboiling point than the desired gasoline product, condensing theseparated gasoline vapors resulting from said fractionation, separatelycracking a relatively heavy reflux condensate produced in saidfractionating operation at a temperature slightly lower than thatemployed in the cracking of said light oil to produce additionalquantities of high anti-knock motor fuel, and introducing the .resultingcracked products into said end portion of said chamber in intimatecontact with the other oil products introduced thereinto.

12. The process of cracking petroleum oils for (ill the formation of ahigh antiknock gasoline and the production of a marketable fuel oil,which comprises heating a relatively heavy distillate oil cracking stockin a confined stream to a cracking temperature of from 875 to 950 F. andpassing the resulting highly heated products through a relatively longtransfer line directly into the lower portion of a separating zone in alarge chamber, separating vapors from unvaporized oil constituents inthe lower portion of said separating zone, preheating a relatively heavyresidue containing fresh charging stock for the process and introducingthe same directly into the hot oil products in said transfer line at apoint about 130 feet along said line from said separating zone wherebythe mingled products in said transfer line are thoroughly mixed andtheir temperatures substantially equalized prior to being dischargedinto said separating zone and the residue in said stock heated to atemperature adapted to produce a low viscosity fuel oil, withdrawing amarketable fuel oil of low viscosity from the bottom of said separatingzone and removing it from the system, passing the vapors separated insaid separating zone from the upper portion thereof and subjecting themto a fractional condensing operation, and condensing a high antiknockmotor fuel product from vapors uncondensed in said fractionatingoperation.

13. A hydrocarbon oil cracking process which comprises passing arelatively heavy reflux distillate produced in the cracking operationthrough a heating zone and heating the same therein to a crackingtemperature under pressure, discharging the heated oil into the lowerportion of a substantially vertical reaction zone in an enlargedvertical chamber maintained under cracking conditions of temperature andpressure, separating the heated oil into vapors and unvaporized oil inthe lower portion of the reaction zone in said chamber, collectingseparated unvaporized oil in the bottom of said chamber and withdrawingit therefrom, simultaneously heating a lighter reflux distillateproduced in the cracking operation in a second cracking zone to a highercracking temperature than that to which said relatively heavy distillatewas heated and then discharging the resulting highly heated productsinto said reaction zone a substantial distance below the top thereof andat a point above the introduction of said heated oil, commingling thehighly heated products introduced into said zone with the firstmentionedvapors, passing the resulting commingled vapors upwardly through thereaction zone and removing the same from the upper portion thereof, andfractionating the vapors removed from the upper portion of said reactionzone to produce said reflux distillates and a final gasoline product.

14. A hydrocarbon oil cracking process which comprises passing arelatively heavy oil through a heating zone and heating the same thereinto cracking temperature under pressure, discharging the heated oil intothe lower portion of a substantially vertical reaction zone in a largevertical chamber maintained under cracking conditions of temperature andpressure, separating the heated oil into vapors and unvaporized oil inthe lower portion of the reaction zone and withdrawing the unvaporizedoil therefrom as it collects in the bottom of the reaction zone,simultaneously heating a lighter oil in a second cracking zone to highercracking temperature than said heavy oil and then discharging the sameinto the reaction zone a substantial distance below the top thereof andabove the point of introduction of said heated oil, thereby preventingcontact between the vapors of the lighter oil and said unvaporized oiland commingling the lighter oil vapors with the first-mentioned vapors,passingthe comingled vapors upwardly through the reaction zone andremoving the same from the upper portion thereof, and fractionating andcondensing the withdrawn vapors.

15. A hydrocarbon oil cracking process which comprises passing arelatively heavy reflux distillate produced in the cracking operationthrough a heating zone and heating the same therein to a crackingtemperature under pressure, discharging the heated oil into the lowerportion of a substantially vertical reaction chamber maintained undercracking conditions of temperature and pressure, separating the heatedoil into vapors and unvaporized oil in the lower portion of the reactionchamber, collecting the unvaporized oil in the bottom of the chamber andwithdrawing the same from the bottom of the chamber and removing it fromthe system, simultaneously heating a lighter reflux distillate producedin the cracking operation in a second cracking zone to a higher crackingtemperature than that to which said relatively heavy distillatewasheated and then discharging the resulting highly heated products intosaid reaction chamber a substantial distance belowthe top thereof and ata point above the introduction of said heated oil, commingling thehighly heated products introduced into said chamber with thefirst-mentioned vapors, passing the resulting commingled vapors upwardlythrough the reaction chamber and removing the same from the upperportion thereof, fractionating the vapors removed from the upper portionof said reaction chamber to produce a heavy condensate of relativelyhigh carbon residue content as well as said reflux distillates and afinal gasoline product, and introducing said heavy condensate directlyinto said reaction zone.

16. A hydrocarbon oil cracking process which comprises passing arelatively heavy oil through a heating zone and heating the same thereinto cracking temperature under pressure, discharg ing the heated oil intothe lower portion of a substantially vertical reaction zone in a largevertical chamber maintained under cracking conditions of temperature andpressure, separating the heated oil into vapors and unvaporized oil inthe lower portion of the reaction zone and withdrawing the separatedunvaporized oil from the lower portion of said reaction zone andremoving it from the system, simultaneously heating a lighter oil in asecond cracking zone to a higher cracking temperature than that to whichsaid relatively heavy oil was heated and then discharging the resultingproducts into said reaction zone a substantial distance below the topthereof and above the point of introduction of said heated oil, therebypreventing contact between the vapors of the lighter oil products andsaid unvaporized oil, and commingling the lighter oil vapors with thefirst-mentioned vapors, passing the commingled vapors upwardly throughsaid reaction zone and removing the same from the upper portion thereof,passing the vapors removed from the upper portion of the reaction zonein heat exchange with a residue-containing fresh oil charging stock andintroducing the resulting preheated charging stock directly into theheated heavy oil introduced into said reaction zone, and fractionatingand condensing the vapors following said heat exchange with said stock.

17. The process of cracking hydrocarbon oils, which comprises passing adistillate oil through a heating and cracking zone and heating the sametherein to a cracking temperature to cause formation of high antiknockconstituents, passing the resulting cracked products into an enlargedreaction zone in a large chamber maintained at a cracking temperatureunder superatmospheric pressure wherein cracking is continued andseparation of vapors from liquid occurs, passing the separated vaporsfrom said reaction zone into a heat exchange zone wherein separation ofvapors and liquid high boiling condensate occurs, passing the separatedvapors from said heat exchange zone to a fractionating tower in whichthe vapors are separated by fractionation to produce a refluxdistillate, conducting said distillate to said heating and crackingzone, passing fresh oil charging stock containing residual constituentsinto said heat exchange zone and therein preheating said stock andcondensing high-er boiling constituents of said vapors, passing saidpreheated stock from said heat exchange zone and combining it withhighly heated products discharged from said heating zone whereby theresulting combined products are brought in intimate contact and theirtemperatures substantially equalized in said en larged reaction zonethereby to reduce the viscosity of the residual products in said stock,col lecting the separated residual products in the bottom of saidenlarged reaction zone and withdrawing the same from the bottom of saidreaction zone as a finished heavy fuel oil.

18. The process of cracking petroleum oils for the formation of a highantiknock gasoline and the production of a marketable fuel oil whichcomprises passing a distillate oil in a confined stream of restrictedcross section through a heating zone and heating and cracking the oiltherein under conditions adapted to produce high antiknock gasolineproducts, conducting the resulting highly heated cracked products fromsaid heating zone into an enlarged reaction zone in a large chamber inwhich vapors are separated from unvaporized oil constituents and thevapors maintained under cracking conditions in said enlarged zone,passing the high temperature cracked vapors from said reaction zone intoa preliminary refluxing zone in heat exchange with preheated chargingstock containing residual constituents of undesired viscosity for fueloil purposes, effecting condensation of some of the heavy constituentsof said vapors particularly the coke-forming constituents and returningsuch condensate directly to said enlarged reaction zone, passing thepreheated charging stock into intimate contact with the highly heatedproducts from said heating zone to break the viscosity of the residualconstituents in said stock, maintaining said stock in contact with saidhighly heated constituents for a sufficient time to effect the desiredconversion of the residual constituents into products of suitably lowviscosity for fuel oil purposes, collecting the unvaporized oilconstituents including the unvaporized portion of said stock in thebottom of said enlarged reaction zone and withdrawing the same therefromas a finished fuel oil, passing the uncondensed vapors from saidpreliminary fractionating zone into a further fractionating zone inwhich a reflux distillate is recovered, and passing said distillate tosaid heating zone.

19. The process of cracking petroleum oils for the formation of a highantiknock motor fuel which comprises producing a relatively high boiling point gas oil fraction and a relatively low boiling point gas oilfraction from the vapors produced in the cracking process, said gas oilfractions being relatively low in carbon residue content, separatelycracking said fractions by heating each fraction to a temperatureparticularly adapted for its conversion in substantial proportion tolower boiling point products, said heating including the heating of therelatively low boiling point gas oil fraction to a substantially highertemperature than that to which the relatively high boiling point gas oilfraction is heated, introducing the resulting highly heated productsinto an enlarged reaction zone in a large chamber in which unvaporizedoil constituents separate and collect in the bottom of the zone, heatinga fresh charging stock containing residual constituents to a temperatureadapted to break the viscosity of the residual constituents andmaintaining it at such temperature for a sumcient time to complete thedesired viscosity breaking operation, introducing said heated chargingstock into said enlarged reaction zone and collecting unvaporizedconstituents thereof in the bottom of said zone, withdrawing theunvaporized oil constituents from the bottom of said reaction zone as afinished fuel oil product, and subjecting the vapors separated in saidenlarged reaction zone to fractional condensation to produce said gasoil fractions and said antiknock motor fuel.

20. The process defined by claim 19 in which the vapors removed fromsaid enlarged reaction zone are subjected to a preliminary refluxingoperation to condense out the heavy coke and carbon-forming constituentsand introducing the resulting heavy reflux condensate into said enlargedreaction zone without passing the same through either of said heatingzones.

BUTLER P. CRITTENDEN.

